Centrifugal air separator for removal of particles



MW m 1955 4 w. R. CARTER 2,709,500

CENTRIFUGAL AIR SEPARATOR FOR REMOVAL OF' PRTICLES Filed May 3l, 1951 2 Sheets-Sheet 2 JNVENTOR.

l/IV ff 1.7mm

@CENTHEFUGL Al? SEPARATOR FR REMVAL 0F PARTICLES Wiiliam il. Carter, Minneapolis, Minn.

Application May 31, 1951, Serial No.. 229,030

6 Claims. (Ci. 183-77) This invention relates to machines and apparatus for removing fine particles from air or other gaseous mediums and for, if desired, classifying particle-removal through the principle of centrifugal separation.

lt is an object of my present invention to provide an extremely eicient gas separating machine or apparatus which will remove the nest particles of dust or other material entrained in a moving gaseous medium through the close cooperation of a high speed centrifuge rotor with a surrounding casing and with a gas withdrawal tube mounted at one end of said casing and extending through one end of said rotor and communicating with the axial portion within such end of the rotor.

A further object is the provision of a centrifugal, rotortype air separator which eliminates the undesirable features of filtering elements, cyclone dust collector systems and which while creating a main, high speed separation vortex, eliminates disturbing turbulence throughout the separation vortex.

A further object is the provision of a centrifugal dust collector having some features in common with my copending application, Serial Number 167,465, filed June l0, i950, now Patent No. 2,633,930, but attaining an extremely high dust removal efcien'cy through the employment of a high speed, hollow, densely apertured rotor body, working in close cooperation with an axial gas-withdrawal tube and spaced rotor casing.

A further object is the provision of a centrifugal air separator or particle remover which will produce a desired vortex and angular velocity of air without employment of any vanes or blades; which will maintain a substantially constant efficiency of separation although the capacity and flow is varied materially and which at a given air capacity, causes substantially no change in pressure drop across the apparatus even though there is a wide variation in the amount, type and particle size of the material to be separated.

With my improved construction, air or other gaseous medium containing fine particles or globules is given substantially the positive angular velocity of the rotor without employment of any vanes or blades, thereby reducing turbulence and the otherwise attendant reduction of particle size through impaction and attrition which in prior art devices, lessens the speed and eiliciency in separation` The foregoing and other objectives will be `more apparent from the following description made in connection with the accompanying drawings, wherein like refer ence characters refer to similar parts throughout the several views and in which:

Fig. l is a vertical section taken axially through an embodiment of my invention, the dotted lines indican ing connection of the gas or air discharge passage with a` blower casing and also, indicatingl an elective alternative connection of the air sealing passage with the discharge end of the blower;

Eig. 2 is a cross section taken on the line 2-2 of Fig. l;

ice

Fig. 3 is a fragmentary detail view showing the lower end and defleetor flanges of an alternative rotor body; and

iiig. Il is a somewhat diagrammatical view partly in side elevation and partly in vertical section showing an embodiment of my invention where a pressure air liow is created through the centrifugal air separator and where air scaling mechanism is employed between the air withdrawal tube of the rotor and the base of the casing, to exclude passage of air from the bottom of the casing into the air discharge passage.

Referring now to Figures 1 to 3 of the drawings, a cylindrical rotor casing 11 is employed, being as shown vertically disposed and having a smooth internal cylindrical wall, a closed top plate or disc .l2 provided with a central and axial air intake passage 12a and a bottom closure plate 13 suitably and removably affixed to the lower end of the cylinder 11. A relatively small, cylin drie-al cap or intake casing 14 is secured to the top 12 of the rotor casing having a tangentially communicating air intake conduit 14a connected therewith and this cap casing is a'lxed with the inner position of a sealing gasket 11th to the central portion of the top plate 12, and has communication through a central aperture 14e with the upper end of the rotor casing 11.

.i provide a hollow centrifuge-rotor comprising a densely perforated, cylindrical shell 15 of a diameter somewhat less than the cylindrical casing 11 and axially mounted within the casing 11- with substantially Wide clearance relative thereto, to leave an annular particlecollecting passage 16 between the rotor and the casing,

The perforations 15a formed in the cylinder shell 15 are of a dimension or dimensions to permit the largest size particles to be removed, to very freely ypass therethrough without any restriction and such perforations are preferably circular, ranging in diameter according to the particular use of the machine, from one eighth of an inch to one half of an inch. Bdth external and internal surfaces of the cylindrical shell 15 are smooth and unobstructed by ribs, corrugations or detents in my preferred form. The cylinder 15 is affixed at its upper end to an imperforate end disc 17 which is disposed in spaced relation to the top plate 12 of the casing and which axially embraces and is affixed by set screw or the like 17a to a vertical rotor shaft 18 having its ends journaled in suitable bearings 18a and 18b provided in the upper and lower ends of my apparatus or machine. The lower end of the cylinder shell 15. as shown, surrounds and is aflixed to a bottom, imperforate end disc 19 which is provided with a relatively large circular aperture surrounding and closely fitting an air-withdrawal tube.20 which in the form illustrated, is aixed to and comprises a part of the rotor,

The air withdrawal tube 20 is open at both of its ends and as shown, is axed to the lower portion of rotor shaft 10 by suitable means such as upper and lower spiders 20a and Zlib respectively provided with radial set screws 20c. The inner end of the air withdrawal tube, therefore extends inwardly a short distance beyond the adjacent end closure 19 of the hollow rotorand is disposed axially thereof. The lower end disc 19 as shown .is suitably aixed by bolts 19a and a spacer collar 1'9b to a perforated distributor disc 21 which is disposed near the' lower end plate 13 of the casing and a sealing gasket 22 is preferably interthe periphery of the withdrawal tube 20.

The lower end of air withdrawal tube 20 extends through a so-called sealing chamber 23 formed in the upper portion of a cap cylinder 24 affixed to the bottom closure disc 13 of the casing and then enters and cornmunicates with the clean air withdrawal passage 25 formed by the lower portion of cap cylinder 2.41. Passage 25 is posed between collar 19t and disc 19, compressed against cylindrical and as shown, has a tangential discharge pas sage 25a which may be connected with the eye or intake of a blower B.

An eliicient and novel mechanism or sealing medium is provided between the periphery of the rotary air withdrawal tube 20 and the air discharge passage 25 to positively prevent flow of air and tine particles or dust from the bottom of the interior of the rotor casing 11 to the clean air discharge passage 25. To this end, the annular sealing chamber 23 is provided surrounding the intermediate lower portion of the withdrawal tube 20 and cornmunicating as shown in full lines, through one or more radial ports 23a with the atmospheric air surrounding my machine or apparatus. The rotary tube 20 works in a clearance relation to apertured portions of the cap member 24 disposed above and below the sealing chamber 23 and to this end, if desired, a series of vertically spaced annular grooves 24a may be supplied in such apertured portions.

In the form of the invention of Fig. 1, since the air discharge passage is connected with the intake of a blower B or some other source of partial vacuum, a slight partial vacuum is set up within casing 16 and within the lower portion thereof. Therefore, since sealing chamber 23 is connected with the atmosphere or a source of gaseous medium under pressure above or at atmospheric pressure, any flow of air or gaseous medium around the air-withdrawal tube 20 will be in an upward direction into the bottom of the casing 11 from the sealing chamber 23. Thus, downward or outward ow of air or any minute particles from the bottom of the rotor casing is excluded and positively prevented.

The bearing 18b for the lower end of the rotor shaft as shown, is supported within a removable heavy plate or disc 26 secured to the bottom of the cap cylinder 24. The lower end of rotor shaft 18 as shown, is provided with a V-pulley 18C which may be driven from a motor or other source of power by an endless V-belt V.

As shown, the lower end of the cylindrical rotor shell 15 is provided with a plurality of circumferentially spaced, particle-discharge passages or slots 15b, the lower edges of which are preferably delined by the inner surface of the closure disc 19. Deilector louvres or anges 15e are preferably formed just above the ports or slots 15b and may be integrally constructed with the shell 15 by cutting the stock of the shell in U-fashion and bending the flaps so cut into positions perpendicular to the axis of the cylindrical shell. In handling certain types of particles it is desirable, as shown in Fig. 3 to aperture or perforate the deilectors or flanges 15e by the drilling or other provision of closely spaced apertures 55 formed therein.

At the lower portion or bottom of the rotor casing 11 and preferably below the bottom closure disc 19 of the rotor, a particle-discharge chamber is formed, having as shown, a lateral discharge passage 27 communicating with a short, depending spout 28 which as shown, is internally threaded at its lower open end to engage and support a particle-collecting container 29.

My apparatus may be supported or mounted in any suitable manner and in the form shown, is supported on four vertical legs 30 which are rigidly afxed to the bottom closure disc 13 of the rotor casing.

Operation InY operation, the centrifuge rotor is driven at relatively high speed, the speed varying within a range depending on the nature of the use. The linear foot travel of the periphery of rotor cylinder 15 may vary from 5000 feet per minute up to 15,000 feet per minute, depending upon the conditions, size and specific gravity of the prevalent particles to be centrifugally extracted from their entrainment with air or some other gaseous medium. Air flow is produced in the'form shown in Figures l to 3, by connection of the air discharge passage 25a with a source of suction or negative pressure such as the inlet of a power blower B. The air intake passage 14a of my machine is connected with a room, chamber or the interior of a machine or apparatus from which particle-laden air is to be withdrawn. The general movement of the air or gaseous medium and the particles entrained thereby in the machine of Figure l, is downwardly. The general movement of the pure air or gaseous medium is inwardly and downwardly while the movement of the heavier particles is centrifugally outward and downwardly in the operation of the apparatus of Figure 1.

The high speed revolution of the hollow rotor including the densely perforated cylindrical shell 15 and its irnperforate top and bottom closure discs 17 and 19, sets up a high speed vortex with an angular velocity of the air equaling or substantially equaling the speed of the rotor.

Since the densely perforated or highly foraminous hollow rotor shell 15 is substantially unobstructed in its interior, neglecting losses due to friction the resulting angular velocity of the air vortex created increases from the peripheral portion of the revolving air within the shell 15 to the axial portion of the shell. The increase of the R. P. M. or angular velocity of air ignoring friction losses is inversely proportional to the diameter of the vortex. Centrifugal force exerted on a particle varies proportional to the square of the R. P. M. Thus, in the operation of my structure, the angular velocity or R. P. M. of the swirling air adjacent the center or axis of the vortex at the area where air or other gaseous medium is withdrawn through the withdrawal tube 20 is at a relatively very high speed, which speed of course is most effective in its centrifugal action in excluding and causing heavier particles to be excluded from the withdrawal tube. The result of the highly efficient centrifuging vortex produced by my apparatus is that an extremely high eciency of separation is obtained. The vortex is substantially free from turbulence and eddy currents since the rotor is unencumbered with arms, vanes, or obstructing parts and since the rotor is smooth and symmetrical in shape. The imperforate upper closure disc 17 acts as a distributor upon the entering air or gaseous medium laden with particles of dust or other material, producing a substantially uniform radial and whirling distribution of the material to be separated, towards the inner peripheral wall of the rotor casing 11.

The vortex created by my rotor of course extends to the annular passage 16 between the rotor shell 15 and the casing 11 and here again, the swirling action is substantially free of any turbulence or eddy currents because of my improved structure. The particles of foreign material such as dust, are centrifugally carried and worked by my apparatus to the annular passage 16 and then to the discharge end of the casing, passing through the lateral passage 27 into the top of the collector container. Gravity assists in the collection of particles.

The perforated disc 21 agitates particles collecting upon the bottom 13 of the casing and in its rotation, assists in the delivery of these partices to the lateral particle outlet 27 which communicates with the top ofthe collection container 29.

The particle discharge slots 15b at the lower end of the rotor shell in the centrifuge action, keeps the bottom of the rotor clear and in this connection, the inturned flanges 15e restrict turbulence and recirculation currents.

In use, an embodiment of my invention utilizing a rotor of approximately six inch diameter and densely perforated at its cylindrical shell with apertures or passages approximating ?y of an inch in diameter, demonstrated an efficiency in excess of 99.99% in the separation of air fromdust particles entrained thereby.

In Fig. 4, a somewhat different embodiment of my improved sealing medium is employed in a system or apparatus wherein air circulation through the rotor and cas* ing is set up by forced circulation rather than by partial vacuum.

In Fig. 4, the apparatus is diagrammatically illustrated, the parts of the rotor, the rotor housing, the intake passage and air withdrawal tube being substantially identical in structure with the form first described and therefore, being identified by like numerals in Fig. 4.

Air or other gaseous medium containing dust or entrained particles of other foreign material is drawn as shown, through a relatively large tube T into the intake of a power blower B and is discharged by that blower tangentially of the casing through a somewhat smaller conduit C into the top cap 14 constituting the intake for the housing l1 of my air separating machine. The rotor l5 of the general structure shown in Fig. l and mounted on rotor shaft lf2 is axially mounted within housing 11i and has affixed thereto the open ended air withdrawal tube 2t! which passes through a sealing chamber 33 generally similar in construction to the sealing chamber 23 of Fig. l and as shown, formed in a cylindrical base member 24 which is secured to the bottom closure 13 of housing lll.

in this form of the invention, a pressure is set up with-- in housing lil and the interior of the rotor slightly in excess of the atmospheric pressure surrounding the housing or casing. The annular sealing passage 33 is closed as shown with the exception of a radial port or passage 33a which is threadedly or otherwise connected with a relatively small conduit 34 having a valve 34a therein, such conduit 34 communicating with the interior of the tube T to cause induction of a flow in the direction illustrated by the arrows under the effect of partial vacuum set up by the axial portion of the blower rotor.

The centrifugal, vortex separation of the gaseous rnedium or air from the particles entrained thereby in the apparatus of Fig. 4 is similar to the operation previously disclosed herein. An efficient seal between the periphery of the air withdrawal tube and the air discharge passage 2" is accomplished by the structure described and illustrated in Fig. 4 since any leakage of air from the lower portion of housing 11 between the periphery of withdrawal tube 20 and the bottom of the casing or the upper portion of the cylindrical member 24 together with line particles entrained thereby, collects in the annular sealing passage 33 and is withdrawn therefrom through the partial vacuum impressed upon the communi eating tube 34. Likewise any leakage of air from the air discharge passage communicating with the lower open end of tube 2d is directed upwardly as indicated by the arrows in Fig. 4, excluding passage of particle-laden air from the air discharge passage, since upward escape of very small amounts of air is also effected by the partial vacuum impressed upon the withdrawal tube 34. The air or other gaseous medium which may contain a small percentage of fine particles is transmitted into the entering air stream of the apparatus which passes into the in let of blower E from the enlarged tube T.

From the foregoing description, it will be seen that in both forms of the invention illustrated, a very highly etiicient centrifuge-separation is obtained between the air or other gaseous medium and any particles, globules or foreign material entrained therein. This highly etilcient separation produces unexpected results and is thought to be due to the close cooperation between a generally cylindrical high speed rotor unobstructed radially or transversely and of smooth wall construction densely perforated with a distribution of the entering air around one end of the periphery of the rotor and with an air withdrawal tube or the equivalent of very small diameter relative to the .rotor with its air admitting end extending axially for some distance into the contines of the rotor at the end opposite its entrance end. With such cooperative structure, a positive and substantially perfect seal is required between the air withdrawal tube at its periphery and the bottom of the rotor and stationary bottom of the rotor housing so that no air containing line particles may become mixed with the pure air or gaseous 6 v medium withdrawn through the interior ofr the' tube. My novel and improved sealing mechanism therefore closely cooperates with other essential parts of my structure to produce an unexpected and highly eiiicient unitary result.

It will of course be understood that various changes may be made in the form, details, arrangement and proportions of the parts without departing from the scope of my invention.

What l claim is:

l. A centrifugal separating machine for removing particles from a particle-laden gaseous stream comprising, a separating chamber through which the moving gaseous stream is passed, a rotor of hollow, symmetrical construction mounted within said chamber in spaced relation to the walls thereof to provide an annularly arranged particle-collecting chamber, means for driving said rotor at high speed on its longitudinal axis, said rotor having an imperforate end portion, said chamber having a gaseous stream inlet at one end thereof adjacent the said imperforate end portion and arranged to direct the incoming flow of said gas stream against said imperforate end portion whereby the incoming flow of said gaseous stream will be deliected radially outward about the periphery of said rotor, said rotor having a densely foraminated peripheral wall of circular cross section dening interiorly an unobstructed passage for substantially the full length of said rotor to permit simultaneous radial and axial movement of the gaseous stream through the rotor, and with the forarninations of such size as to freely permit passing of particles radially in either direction therethrough during rotor revolution, a clean gas withdrawal tube of substantially smaller diameter than said rotor connected at its outer end with a source of partial vacuum and having an inner open end extending axially within the interior of said rotor through one end thereof so that upon rotation of the rotor the passage of the stream within the rotor to the clean gas withdrawal tube is along an unobstructed spiral vortex-like path decreasing in diameter from one end of said rotor to the said withdrawal tube, said extended inner end of said tube functioning to concentrate the apex of said vortex-like path at a location inwardly from said one end of the rotor whereby the angular velocity of the stream while traveling in said spiral vortex-like path increases with the decrease in diameter of the path to subject the remaining particles carried by the stream to an increasing centrifugal force thereby separating the particles from the gas: and directing the particles radially through said foraminations to the space peripherally of the rotor for discharge.

2. The structure set forth in claim l, wherein said rotor and said clean gas withdrawal tube are axially mounted upon a common shaft, said shaft extending through said rotor and being connected with said driving means.

3. The structure set forth in claim l, wherein said rotor has also a second imperforate end portion, one of said imperforate end portions surrounding said clean gas withdrawal tube in concentric relation and having sealed connection therewith.

4, The invention according to claim l, wherein the said end of the rotor is spaced from an end of the chamber, and a particle outlet opening in a side of the chamber in a plane lying between the said end of the rotor and the adjacent end of the chamber.

5, The invention according to claim l, with a distributor disk encircling the tube in a plane between and spaced from the said one end of the rotor end wall and an adjacent end wall of the chamber and coupled to the rotor to turn therewith.

6. The invention according to claim l wherein said rotor peripheral wall has a plurality of horizontal slots therethrough in close proximity to the said one end wall thereof, and an inwardly extending iiange carried by said References Cited inthe le of this patent UNITED STATES PATENTS Whitehill Mar. 29, 1887 Van Gelder Apr. 26, 1898 Goodloe Nov. 15, 1927 A MacFarland June 3, 1941 10 Zeitlin et a1 Aug. 12, 1947 S Daugherty Oct. 11, 1949 Niederkorn Mar. 27, 1951 Korn Oct. 2, 1951 FOREIGN PATENTS France Mar. 21, 1908 Great Britain June 11, 1925 Germany Mar. 23, 1925 France Ian. l2, 1927 

1. A CENTRIFUGAL SEPARATING MACHINE FOR REMOVING PARTICLES FROM A PARTICLE-LADEN GASEOUS STREAM COMPRISING, A SEPARATING CHAMBER THROUGH WHICH THE MOVING GASEOUS STREAM IS PASSED, A ROTOR OF HOLLOW, SYMMETRICAL CONSTRUCTION MOUNTED WITHIN SAID CHAMBER IN SPACED RELATION TO THE WALLS THEREOF TO PROVIDE AN ANNULARLY ARRANGED PARTICLE-COLLECTING CHAMBER, MEANS FOR DRIVING SAID ROTOR AT HIGH SPEED ON ITS LONGITUDINAL AXIS, SAID ROTOR HAVING AN IMPERFORATE END PORTION, SAID CHAMBER HAVING A GASEOUS STREAM INLET AT ONE END THEREOF ADJACENT THE SAID IMPERFORATE END PORTION AND ARRANGED TO DIRECT THE INCOMING FLOW OF SAID GAS STREAM AGAINST SAID IMPERFORATE END PORTION WHEREBY THE INCOMING FLOW OF SAID GASEOUS STREAM WILL BE DEFLECTED RADIALLY OUTWARD ABOUT THE PERIPHERY OF SAID ROTOR, SAID ROTOR HAVING A DENSELY FORAMINATED PERIPHERAL WALL OF CIRCULAR CROSS SECTION DEFINING INTERIORLY AN UNOBSTRUCTED PASSAGE FOR SUBSTANTIALLY THE FULL LENGTH OF SAID ROTOR TO PERMIT SIMULTANEOUS RADIAL AND AXIAL MOVEMENT OF THE GASEOUS STREAM THROUGH THE ROTOR, AND WITH THE FORAMINATIONS OF SUCH SIZE AS TO FREELY PERMIT PASSING OF PARTICLES RADIALLY IN EITHER DIRECTION THERETHROUGH DURING ROTOR REVOLUTION, A "CLEAN" GAS WITHDRAWAL TUBE OF SUBSTANTIALLY SMALLER DIAMETER THAN SAID ROTOR CONNECTED AT ITS OUTER END WITH A SOURCE OF PARTIAL VACUUM AND HAVING AN INNER OPEN END EXTENDING AXIALLY WITHIN THE INTERIOR OF SAID ROTOR THROUGH ONE END THEREOF SO THAT UPON ROTATION OF THE ROTOR THE PASSAGE OF THE STREAM WITHIN THE ROTOR TO THE "CLEAN" GAS WITHDRAWAL TUBE IS ALONG AN UNOBSTRUCTED SPIRAL VORTER-LIKE PATH DECREASING IN DIAMETER FROM ONE END OF SAID ROTOR TO THE SAID WITHDRAWAL TUBE, SAID EXTENDED INNER END OF SAID TUBE FUNCTIONING TO CONCENTRATE THE APEX OF SAID VORTEX-LIKE PATH AT A LOCATION INWARDLY FROM SAID ONE END OF THE ROTOR WHEREBY THE ANGULAR VELOCITY OF THE STREAM WHILE TRAVELING IN SAID SPIRAL VORTEX-LIKE PATH INCREASES WITH THE DECREASE IN DIAMETER OF THE PATH TO SUBJECT THE REMAINING PARTICLES CARRIED BY THE STREAM TO AN INCREASING CENTRIFUGAL FORCE THEREBY SEPARATING THE PARTICLES FROM THE GAS AND DIRECTING THE PARTICLES RADIALLY THROUGH SAID FORAMINATIONS TO THE SPACE PERIPHERALLY OF THE ROTOR FOR DISCHARGE. 